<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>java</title>
</head>
<body>

<p>java</p>
<button onclick="Function()">点击这里</button>
<p id="demo"></p>
<script>
function Function(){
	var x="";
	var time=new Date().getHours();
	if (time<20){
		x="java";
    }
	document.getElementById("demo").innerHTML=x;
}
</script>

</body>
</html>
